This invention relates generally to software architectures and more specifically to software for automatic test systems.
Automatic test systems (referred to generally as “testers”) are used in the manufacture of semiconductor devices. Often, a semiconductor device is tested at more than one stage during its manufacture and further processing of the device is determined by the results of the test. In some instances, a device that fails a test is discarded. In other instances, devices can be repaired. For example, the device might be constructed with redundant circuitry. If a faulty portion of the device is identified through testing, the defective circuitry might be disconnected and a redundant circuit element connected in its place. In yet other cases, testing is used for grading of parts. For example, some devices operate only up to a certain speed or only operate at a range of temperatures that is less than the intended operating range of the device. These devices might be separated from other devices that fully meet the design specification and then specially packaged or sold as lower grade parts. Regardless of the specific actions taken in response to the testing, testing is an important part of the manufacturing process.
It is highly desirable for an automatic test system to be as easy to use as possible. One way that ease of use might be achieved is through the provision of software.
U.S. Pat. No. 5,910,895 entitled Low Cost, Easy To Use Automatic Test System Software by Proskauer et al. describes a software system for an automatic test system that is based on using a commercially available spread sheet program to represent the data and program flow needed to define a test program. U.S. Pat. No. 6,047,293 entitled System For Storing And Searching Named Device For Parameter Data In A Test System For Testing An Integrated Circuit by Blitz describes software that facilitates programming of a test system. U.S. Pat. No. 5,828,674 entitled Production Interface For An Integrated Circuit Test System describes a software system, also for automatic test equipment, that makes it easy to provide a user interface to the automatic test system. U.S. patent application Ser. No. 09/417034 entitled Easy to Program Automatic Test Equipment filed Oct. 12, 1999 by Kittross, et al. describes automatic test system that uses a combination of programming techniques to facilitate easy programming of a test while allowing very complex programs to be written. The foregoing are all hereby incorporated by reference.
The foregoing patents are assigned to Teradyne, Inc. of Boston, Mass., USA. Teradyne provides for its test systems a highly successful programming environment called IG-XL that employs techniques described in the foregoing patents.
Notwithstanding the success of that programming environment, it would be desirable to provide an improved software environment. We have recognized that one area for improvement comes about because traditional software for automatic test equipment contains drivers that run the tester hardware. It is traditional for testers to include hardware instruments that are specially adapted for certain test functions. For example, some instruments generate or measure RF signals. Other instruments generate digital signals, while others perform functions unique to testing of semiconductor memories. Instruments for a test system are often developed after the test system is released, either because a need for a new instrument is identified or because it is not possible to time development of a test system and all instruments to be available at the same time.
As new instruments are developed, the software environment must be modified to incorporate control of the new instruments. Traditionally, software has been modified by releasing new versions of the software. For testers, releasing new software can sometimes be a disadvantage. Semiconductor manufacturers often “qualify” test programs they have written to test the semiconductors they are manufacturing. The qualification step is important for the semiconductor manufacturer to have a high degree of confidence that devices that pass testing are actually good devices and those that fail testing are actually faulty devices. If a new release of the software is issued, it might be necessary for the semiconductor manufacturer to re-qualify all of its test programs.
We have also recognized that another area for improvement arises because of the rapid pace of technical advancement in the semiconductor industry. New generations of devices are developed that are usually larger and faster than the preceding generation, requiring new testers. It would be highly desirable if test programs could be quickly developed for the new generation of devices, even if they are tested on new testers.